The field of the present invention is that of internal combustion engine control and management.
The problem underlying the present invention is that of limiting the emission of particles in the exhaust of an internal combustion engine. The standards in force are becoming increasingly strict and it is appropriate to further optimize engine management in order to limit the amount of particulates emitted by an engine.
The present invention is more particularly concerned with engines referred to as direct injection engines, which means to say engines comprising at least one combustion chamber into which fuel is injected directly (as opposed to engines in which a mixture of air and fuel formed upstream of the combustion chamber is introduced into the latter).
An injection system is controlled by an electronic unit. The engine operates according to a predetermined cycle and, for each cycle, a quantity (possibly zero) of fuel is determined by the electronic unit according to predefined parameters. The quantity of fuel thus defined is injected into the combustion chamber (we are considering the case of direct injection) in each cycle. Of course, it is important to inject the fuel at the correct moment during the cycle. It has also been noticed that under certain conditions, it is preferable to inject the fuel not in a single shot but in several.
Thus, the engine electronic control and management unit determines, in addition to the quantity to inject and the moment at which the injection is to be performed, whether to form a “single-shot” or a “multi-shot” injection. The strategies known from the prior art for switching from a single-shot injection regime to a multi-shot injection regime or vice versa are dependent on parameters such as the engine speed and/or the engine temperature (which corresponds to the temperature of the coolant) and/or to the engine load, etc.
The novel idea underlying the invention is that of believing that modifying the strategy governing the changeover between single-shot and multi-shot injection regimes may make it possible to limit the quantities of particulates emitted at the engine outlet.
It is therefore an object of the present invention to provide a novel strategy for managing injection in an engine that makes it possible to further limit the amount of particulates emitted by an engine.
As is known to those skilled in the art, it is when an engine is cold that it emits the most particulates. The invention therefore notably seeks to improve the fuel injection strategy in a direct injection engine when the engine is cold.